Chafing dishes are widely used for buffet type food service, serving hors d'oeuvres, and other purposes. Such chafing dishes typically include a water pan supported by a leg and a bracing structure. A heat source is used to heat the water in the water pan. A food pan is supported by the water pan above the level of the water.
In most instances flames from canned fuels are used as the heat source. Other chafing dishes have been proposed which use electrical heaters rather than flames to heat the water. But, the known electrically heated chafing dishes also have drawbacks. Some prior electric heater elements project through holes in the water pan to provide terminals for connection to a power source. These holes obviously must be sealed and are themselves a source of service trouble.
Heater elements which are physically connected to the water pan with portions of the elements projecting through holes in the water pan, are difficult to clean. Since they are difficult to clean the elements tend to suffer from scale build-up which reduces efficiency and degrades the performance of the unit.
Other prior proposals placed electric heating elements beneath the water pan. These proposals required support structure adding significantly to complexity and cost.
With canned fuels, the fuel is either an alcohol base material or an oil and wick arrangement. The alcohol materials tend to vapor lock so that flame size varies and produces uneven heat. Diaphragms are sometimes provided that are adjustable to control the size of the flame and with it hopefully the amount of heat produced. The problem with these diaphragms is that with the tendency of the alcohol type fuel to vaporize, the flame is often extinguished.
With wick and oil heat sources, the only ability to control the temperature of the flame is by spreading of the wick to increase the size of the flame. Thus, at best there is very limited control of temperature using a flame arrangement.
Canned heat sources are costly and wasteful. Typically after a food service the cans which have been used will be disposed of and new cans will be used at a subsequent service to be sure that there is adequate fuel at the subsequent service. Moreover, cans of fuel typically must be bought in quantity which ties up both capital and storage space.
The chafing dish described and claimed in Pat. No. 5,045,672 issued Sep. 3, 1991 (the Prior Patent) was very favorably received in test installations, but it had one major drawback. Specifically, it was necessary to provide either specialized water or food pans notched to receive a heating element.